NASA's NuSTAR Mission Proves Superstar Eta Carinae Shoots Cosmic Rays

Amber Fields |Saturday, July 07, 2018

An image of Eta Carinae

Eta Carinae, for example, is a binary star system that sits around 7,500 light years from Earth, and it's so incredibly extreme that when it fires cosmic rays off into space they actually manage to reach us here on Earth.

A star system containing two huge suns is blasting cosmic rays into space and NASA scientists have found that the radiation is making its way towards Earth on intergalactic winds.

Eta Carinae contains a pair of massive stars whose orbits can push them closer to Earth every 5.5 years.

In five and half years, the two stars in the system come within 230 million kilometers of each or roughly the average distance between Sun and Mars. It is accelerating particles to high energies and some of those particles are heading to Earth in the form of cosmic rays.

But because these particles like electrons, protons and atomic nuclei carry an electrical charge, they veer off course whenever they encounter magnetic fields.

NASA's NuSTAR mission has proven that some of the cosmic rays reaching the Earth from outer space are coming from the superstar Eta Carinae.

Both of the stars are constantly puking out charged particles at extremely high speeds, with the larger star's wind slamming into that of the smaller star, creating massive waves of energy that is being blown out into space. But Fermi's vision isn't as sharp as X-ray telescopes, so astronomers couldn't confirm the connection.

"We know the blast waves of exploded stars can accelerate cosmic ray particles to speeds comparable to that of light, an incredible energy boost", said lead author Kenji Hamaguchi, an astrophysicist at NASA's Goddard Space Flight Center.

Low-energy, or soft, X-rays originate in gas at the interface of colliding stellar winds where temperatures can exceed 40 million degrees Celsius (79 million degrees Fahrenheit).

The radiation, which is believed to contain energy greater than one billion electron volts, is riding intergalactic winds, quickly making its way through the great expanse. By combining both newly taken and archival data, researchers confirmed that NuSTAR observations acquired between March 2014 and June 2016 coincide with lower-energy X-ray observations from the European Space Agency's XMM-Newton satellite over the same period. Since its launch in 2012, it has been detecting X-rays above 30,000 electron volts.

The Eta Carinae system is made up of two massive stars that produce powerful interacting stellar winds. The star system famously brightened in 1843, briefly becoming the second brightest "star" in the sky. "Our analysis indicates Eta Carinae is one of them", Hamaguchi said.

It was only until this present study published in Nature Astronomy on July 2 that scientists are certain these cosmic rays were coming from Eta Carinae. The best explanation for hard X-rays is electrons accelerated in violent shock waves along the boundary of the colliding stellar winds, suggesting that these stellar winds are more dramatic than expected. "But until NuSTAR was able to pinpoint the radiation, show it comes from the binary and study its properties in detail, the origin was mysterious".

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